Null circular geodesics, closed orbits on which massless particles
(photons, gravitons) can orbit a central black hole, provide
valuable information about the physical characteristics of the
corresponding curved spacetime [1]}, [2]}, [3]}, [4]}. Due to
their importance in astrophysical [5]}, [6]}, cosmological
[7]}, and theoretical
[8]}, [9]}, [10]}, [11]}, [12]}, [13]}, [14]}, [15]}, [16]}
studies of black-hole
spacetimes , light-like circular geodesics have attracted over the years a good deal of
attention from physicists and mathematicians.
